1. Field of the Invention
A vacuum activate power take off assembly to drive a winch on a vehicle wherein the vacuum or negative pressure is selectively directed from the internal combustion engine of the vehicle for engagement in disengagement of the winch with the transmission of the vehicle.
2. Description of the Prior Art
The structure of a winch mounted on a vehicle which is commonly known as a tow truck for purposes of towing other vehicles or for other lifting or pulling purposes is, of course, very well known in the art. The U.S. Pat. No. 4,099,628 to Richardson, is representative of such a towing vehicle. Richardson shows a tow truck having a frame and drive train for a proportion of the vehicle including a turntable mounted on the frame for rotation of the boom assembly by vertical axis the Richardson patent is directed to numerous structural components which accomplish adjustment of the boom assembly about a horizontal axis including a drive assembly for the rotatable turntable. In this structure, the winch is electrically operated independently of the vehicle train and is controlled by a control box electrically coupled to the drive motors of a cable connected to the vehicle by means of a self-winding cable wheel. A set of controls is provided in the passenger compartment or cab of the vehicle.
Similarly, Francis, U.S. Pat. No. 2,604,302, discloses a truck crane to be mounted on a vehicle including a pulling winch.
The patent to McKinney, et al, discloses a cable injecting device which operates off a pressure fluid reservoir and is activated thereby through control and direction of the fluid under pressure to the drive portions of the assembly.
In addition to the above, the patent to Workman, U.S. Pat. No. 3,633,875, discloses a pneumatic balancing hoist comprising a frame rotatably supporting a hollow drum upon which is wound a cable or similar flexible element. The hollow drum includes a pressure chamber containing a piston movable in response to pressurization of the chamber. A piston includes a plurality of cam rollers each of which are engaged by a rotatable cam member. Workman is absent any type of negative pressure take off being controlled by a fluid operable switch to serve to selectively connect or disengage the drive mechanism of a vehicle mounted winch to the transmission thereof.
In typical and well-known fashion, winch is mounted on vehicles and used in tow truck are generally "mechanically" connected and disconnected to a power take off portion of the transmission of the vehicle. The mechanical operation of conventional and/or prior art structures is accomplished by means of metal cables or the like physically manipulated by an operator. Due to the friction involved in the manipulation and mechanical positioning of interconnecting drive linkage of the power take off with the drive train of the winch itself considerable force is required by the operator to establish an operative drive connection to the winch. This is inconvenient, time consuming and generally undesirable. Accordingly, there is a need in this area for an assembly which more conveniently and effectively serves to activate the winch or more specifically the drive chain associated therewith such that the winch is selectively operable for use in the field.